Role of risk factors for major coronary heart disease events with increasing length of follow up

BACKGROUND: It has been suggested that the predictive value of certain risk factors for coronary heart disease (CHD) measured at one point in time diminishes with increasing length of follow up. DESIGNS AND METHODS: The relation was examined between a wide range of risk factors and the risk of major CHD events over 15 years' total (cumulative) follow up and for three separate five year periods (0-5.0, 5.1-10.0, and 10.1-15.0 years) in men with and without diagnosed CHD in a large prospective study of 7735 men aged 40-59 years. SETTING: General practices in 24 towns in the UK. RESULTS: The cumulative CHD event rate for all men was 9.4/1000 person-years for the 15 years of follow up. In men with no recall of a diagnosis of CHD, the established risk factors-serum total cholesterol, high density lipoprotein cholesterol, systolic and diastolic blood pressure, physical activity, body mass index (BMI), alcohol intake, diabetes mellitus, parental history, and evidence of CHD on chest pain questionnaire or on ECG-were predictive of CHD events occurring in the three specific periods after baseline measurement. Blood pressure (systolic and diastolic) was still predictive of events occurring 10.1-15.0 years later with some attenuation in the relative risk associated with systolic blood pressure. The risks associated with blood glucose and serum insulin concentration, factors measured with greater imprecision, attenuated with longer follow up and were not predictive of events occurring 10. 1-15.0 years later. In men with recall of diagnosed CHD, the absolute risk was very high (38.8/1000 person-years); only cigarette smoking, BMI, total cholesterol, and serum insulin were predictive of CHD events occurring 10.1-15.0 years later. CONCLUSION: In men without recall of diagnosed CHD most major risk factors measured in middle age predict risk of CHD events occurring in up to 15 years of follow up, both cumulatively and in the three separate five year periods. Risk factors measured at one point in time in middle age may be regarded as reliable indicators for long term prognosis of major CHD events on a group basis, despite the changes that may take place in these risk factors in some individuals during prolonged follow up.